. Cold-blooded vertebrates: part I. Fishes. Fishes; Amphibians; Reptiles. THE STRUCTURE OF A FISH mouth cavity, although in embryo sharks and a few other forms external gills (the gill tufts just mentioned), resem- bling those of the fresh-water newt, are present (Fig. 36). Structurally three main types occur among fishes. The lampreys, for example, have purse-shaped gills situated in. Fig. 36. Ventral view of larval frill shark, Chlamydoselachus anguinetts, showing external gill tufts. .After Garman several depressions on each side of the anterior part of the body. Each sac is lined with frin
. Cold-blooded vertebrates: part I. Fishes. Fishes; Amphibians; Reptiles. THE STRUCTURE OF A FISH mouth cavity, although in embryo sharks and a few other forms external gills (the gill tufts just mentioned), resem- bling those of the fresh-water newt, are present (Fig. 36). Structurally three main types occur among fishes. The lampreys, for example, have purse-shaped gills situated in. Fig. 36. Ventral view of larval frill shark, Chlamydoselachus anguinetts, showing external gill tufts. .After Garman several depressions on each side of the anterior part of the body. Each sac is lined with fringes well supplied with blood capillaries, and the whole series of sacs is supported by a so-called branchial basket, formed of cartilage. Sharks and rays, as well as a few other forms, have an other type known as plate gills. These structures are membranous laminae, or thin plates, attached to cartilagi- nous arches, called gill arches. The laminae in this type of gill, like the fringes in the lampreys, are richly supplied with small blood vessels. In the sharks and rays each gill has a separate opening, known as a gill slit, of which usu- ally five are present on each side (see Plate 15). Finally, the ordinary fishes, including the bony fishes, have fringe gills (Fig. 37). That is to say, gill filaments, or fringes, are attached to the outer edge of the supporting bony gill arches, the fringes usually occurring in two rows. The length and the number of fringes present vary greatly among species, probably in proportion to the amount of oxygen needed by different fishes. Fishes which have this type of gill have all the gill arches, which generally con- sist of four pairs, in a single cavity, the branchial chamber, which is well protected by bony gill covers and usually has a single opening on each side. This further differenti- [85]. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appeara
Size: 3341px × 748px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, booksubj, booksubjectfishes, booksubjectreptiles
